Retinal characteristics of myopic eyes in a semi-rural UK population

Abstract

All levels of myopia are associated with an increased risk of ocular diseases such as glaucoma, and retinal detachment. The prevalence of myopia is increasing at an alarming rate across the globe so an increase in ocular morbidity would be expected unless action is taken. The studies in this thesis were carried out to investigate how the retina, and optic nerve head change in appearance at different levels of myopia. Identification of signs indicating future progression would allow targeting of interventions to minimise the ultimate degree of myopia. This thesis describes four community-based studies investigating retinal appearance in myopic eyes. A mixture of retrospective cross-sectional and longitudinal assessments using previously obtained digital fundus images are presented, along with a prospective cross-sectional study of the peripheral retina. The participants had myopia ≤-0.50 D and were mainly of white European ethnicity. Crescent width was found to increase with both age and level of myopia. Those with inferior-temporally located crescents had the highest levels of myopia. Tilted discs were associated with higher levels of myopia and smaller optic discs. Upon longitudinal assessment of disc measures, the optic cup measures, and crescent width were found to increase. Peripheral retinal lesions were observed in 27 % of eyes. Pigmentary degeneration was the most frequently observed and was associated with increasing age and the widest crescents. White without pressure was found in 5.8 % of eyes and was associated with a higher magnitude of myopia. Static retinal vessel analysis showed no significant relationships between retinal vessel calibre summary measures and myopia, age, or optic nerve head measures. The position of the myopic crescent is a possible predictor of future myopic progression. Further longitudinal study is needed to investigate this. The vertical disc diameter remained constant justifying the use of the quotient of the maximum crescent width to vertical disc diameter to determine crescent width change without the need for magnification correction.